Grilles are widely used in vehicles to allow air to enter for engine cooling. A vehicle grille is typically located at the front of the engine compartment of the vehicle. Grille shutters are used to control air flow through the grilles. Grille shutters can improve the overall fuel efficiency of a vehicle. FIGS. 1 and 2 illustrate a traditional vehicle grille shutter 10 that includes a frame 12 and a plurality of grille flaps 14 rotatably supported by the frame 12. The grille flaps 14 are linked together by a linkage 16 and driven by a input mechanism 18 to rotate between a fully closed position (as shown in FIG. 1) and a fully open position (as shown in FIG. 2). The input mechanism 18 mates with an output of an actuator. When the grille flaps 14 are in partially or fully open position, openings 20 between adjacent flaps 14 allows air to flow there through to cool the radiator and the engine of the vehicle. When the grille flaps 14 are in the fully closed position, the openings 20 are closed and outside air is blocked by the flaps 14 in order to improve fuel efficiency when the vehicle is in motion or at a temperature below a threshold value.
A pair of stop projections 22 are formed on the frame 12. When the flaps 14 rotate to the fully closed position, as shown in FIG. 1, further rotation of the flaps 14 is stopped by contact between adjacent flaps 14. When the flaps 14 rotate to the fully open position, as shown in FIG. 2, further rotation of the flaps 14 is stopped by contact between the stop projections 22 and at least one of the flaps.
In such a vehicle grille shutter arrangement, the stopping system is external to the actuator and the actuator torque stresses the mechanical parts of the grille shutter, including the stop projections, the flap and the linkage. The stresses could deform or even break the grille flaps. To avoid this problem, the mechanical parts are required to be made of a strong material. However, this makes the grille shutter heavier and less cost efficient. In addition, the external stopping system brings spatial constraints to the mechanical parts outside the actuator.